// Mesh shader for the 3D viewport.
//
// Group 0: Camera uniform (view-projection, eye position)
// + shadow atlas texture + comparison sampler
// + Lights uniform (up to 8 light sources, shadow parameters)
// + ClipPlanes uniform (up to 6 user-defined half-space clipping planes)
// + ShadowAtlas uniform (CSM matrices, cascade splits, PCSS params).
// Group 1: Object uniform (per-object model matrix, material properties,
// selection flag, wireframe flag, PBR params)
// + Albedo texture (binding 1) + sampler (binding 2)
// + normal map (binding 3) + AO map (binding 4).
//
// Lighting: Blinn-Phong (ambient + diffuse + specular) with multi-light support.
// Cook-Torrance PBR when object.use_pbr != 0.
// Shadow mapping: CSM with atlas-based cascade selection.
// PCF (3x3) or PCSS (blocker search + variable-width PCF) via shadow_atlas.shadow_filter.
// Selection: orange tint when object.selected == 1u.
// Wireframe: gray colour override when object.wireframe == 1u.
// Section views: fragment discarded when world_pos fails any active clip plane.
// Normal maps: tangent-space normal mapping via TBN when object.has_normal_map != 0u.
// AO maps: ambient occlusion applied to ambient + diffuse when object.has_ao_map != 0u.
struct Camera {
view_proj: mat4x4<f32>,
eye_pos: vec3<f32>,
_pad: f32,
forward: vec3<f32>,
_pad1: f32,
inv_view_proj: mat4x4<f32>,
view: mat4x4<f32>,
};
// Single light entry : 128 bytes.
struct SingleLight {
light_view_proj: mat4x4<f32>, // 64 bytes (shadow matrix, lights[0] only)
pos_or_dir: vec3<f32>, // 12 bytes
light_type: u32, // 4 bytes (0=directional, 1=point, 2=spot)
colour: vec3<f32>, // 12 bytes
intensity: f32, // 4 bytes
range: f32, // 4 bytes
inner_angle: f32, // 4 bytes
outer_angle: f32, // 4 bytes
spot_direction: vec3<f32>, // 12 bytes
_pad: vec2<f32>, // 8 bytes
};
struct Lights {
count: u32,
shadow_bias: f32,
shadows_enabled: u32,
_pad: u32,
sky_colour: vec3<f32>,
hemisphere_intensity: f32,
ground_colour: vec3<f32>,
_pad2: f32,
lights: array<SingleLight, 8>,
ibl_enabled: u32,
ibl_intensity: f32,
ibl_rotation: f32,
show_skybox: u32,
};
// Clip planes uniform : 112 bytes.
struct ClipPlanes {
planes: array<vec4<f32>, 6>,
count: u32,
_pad0: u32,
viewport_width: f32,
viewport_height: f32,
};
// Shadow atlas uniform : 416 bytes.
struct ShadowAtlas {
cascade_vp: array<mat4x4<f32>, 4>, // 256 bytes
cascade_splits: vec4<f32>, // 16 bytes
cascade_count: u32, // 4 bytes
atlas_size: f32, // 4 bytes
shadow_filter: u32, // 4 bytes (0=PCF, 1=PCSS)
pcss_light_radius: f32, // 4 bytes
atlas_rects: array<vec4<f32>, 8>, // 128 bytes
};
// Per-object uniform : 208 bytes.
struct Object {
model: mat4x4<f32>,
colour: vec4<f32>,
selected: u32,
wireframe: u32,
ambient: f32,
diffuse: f32,
specular: f32,
shininess: f32,
has_texture: u32,
use_pbr: u32,
metallic: f32,
roughness: f32,
has_normal_map: u32,
has_ao_map: u32,
has_attribute: u32,
scalar_min: f32,
scalar_max: f32,
_pad_scalar: u32,
nan_colour: vec4<f32>, // offset 144
use_nan_colour: u32, // offset 160
use_matcap: u32, // offset 164
matcap_blendable: u32, // offset 168
unlit: u32, // offset 172
use_face_colour: u32, // offset 176
uv_vis_mode: u32, // offset 180 : 0=off 1=checker 2=grid 3=localcheck 4=localrad
uv_vis_scale: f32, // offset 184 : tile frequency multiplier
backface_policy: u32, // offset 188 : 0=Cull 1=Identical 2=DiffColour 3=Tint 4..7=Pattern
backface_colour: vec4<f32>, // offset 192
has_warp: u32, // offset 208
warp_scale: f32, // offset 212
_pad_warp0: u32, // offset 216
_pad_warp1: u32, // offset 220
};
struct ClipVolumeEntry {
volume_type: u32,
_pad_a: u32,
_pad_b: u32,
_pad_c: u32,
center: vec3<f32>,
radius: f32,
half_extents: vec3<f32>,
_pad1: f32,
col0: vec3<f32>,
_pad2: f32,
col1: vec3<f32>,
_pad3: f32,
col2: vec3<f32>,
_pad4: f32,
}
struct ClipVolumeUB {
count: u32,
_pad_a: u32,
_pad_b: u32,
_pad_c: u32,
volumes: array<ClipVolumeEntry, 4>,
};
@group(0) @binding(0) var<uniform> camera: Camera;
@group(0) @binding(1) var shadow_map: texture_depth_2d;
@group(0) @binding(2) var shadow_sampler: sampler_comparison;
@group(0) @binding(3) var<uniform> lights_uniform: Lights;
@group(0) @binding(4) var<uniform> clip_planes: ClipPlanes;
@group(0) @binding(5) var<uniform> shadow_atlas: ShadowAtlas;
@group(0) @binding(6) var<uniform> clip_volume: ClipVolumeUB;
@group(0) @binding(7) var ibl_irradiance: texture_2d<f32>;
@group(0) @binding(8) var ibl_prefiltered: texture_2d<f32>;
@group(0) @binding(9) var ibl_brdf_lut: texture_2d<f32>;
@group(0) @binding(10) var ibl_sampler: sampler;
@group(0) @binding(11) var ibl_skybox: texture_2d<f32>;
fn clip_volume_test(p: vec3<f32>) -> bool {
for (var i = 0u; i < clip_volume.count; i = i + 1u) {
let e = clip_volume.volumes[i];
if e.volume_type == 2u {
let d = p - e.center;
let local = vec3<f32>(dot(d, e.col0), dot(d, e.col1), dot(d, e.col2));
if abs(local.x) > e.half_extents.x
|| abs(local.y) > e.half_extents.y
|| abs(local.z) > e.half_extents.z {
return false;
}
} else if e.volume_type == 3u {
let ds = p - e.center;
if dot(ds, ds) > e.radius * e.radius { return false; }
} else if e.volume_type == 4u {
let axis = e.col0;
let d = p - e.center;
let along = dot(d, axis);
if abs(along) > e.half_extents.x { return false; }
let radial = d - axis * along;
if dot(radial, radial) > e.radius * e.radius { return false; }
}
}
return true;
}
@group(1) @binding(0) var<uniform> object: Object;
@group(1) @binding(1) var obj_texture: texture_2d<f32>;
@group(1) @binding(2) var obj_sampler: sampler;
@group(1) @binding(3) var normal_map: texture_2d<f32>;
@group(1) @binding(4) var ao_map: texture_2d<f32>;
@group(1) @binding(5) var lut_texture: texture_2d<f32>;
@group(1) @binding(6) var<storage, read> scalar_buffer: array<f32>;
@group(1) @binding(7) var matcap_texture: texture_2d<f32>;
@group(1) @binding(8) var<storage, read> face_colour_buffer: array<vec4<f32>>;
@group(1) @binding(9) var<storage, read> warp_buffer: array<f32>;
@group(1) @binding(10) var lut_sampler: sampler;
struct VertexIn {
@location(0) position: vec3<f32>,
@location(1) normal: vec3<f32>,
@location(2) colour: vec4<f32>,
@location(3) uv: vec2<f32>,
@location(4) tangent: vec4<f32>,
@builtin(vertex_index) vertex_index: u32,
};
struct VertexOut {
@builtin(position) clip_pos: vec4<f32>,
@location(0) colour: vec4<f32>,
@location(1) world_normal: vec3<f32>,
@location(2) world_pos: vec3<f32>,
@location(3) uv: vec2<f32>,
@location(4) world_tangent: vec4<f32>,
@location(5) scalar_val: f32,
// 1.0 if the source scalar vertex value was NaN, 0.0 otherwise.
// Detected in vs_main before interpolation can corrupt the NaN bit pattern.
@location(6) is_nan_scalar: f32,
@location(7) face_colour: vec4<f32>,
};
@vertex
fn vs_main(in: VertexIn) -> VertexOut {
var out: VertexOut;
var local_pos = in.position;
if object.has_warp != 0u {
let wi = in.vertex_index * 3u;
let warp_len = arrayLength(&warp_buffer);
if wi + 2u < warp_len {
local_pos += vec3<f32>(warp_buffer[wi], warp_buffer[wi + 1u], warp_buffer[wi + 2u]) * object.warp_scale;
}
}
let world_pos = object.model * vec4<f32>(local_pos, 1.0);
out.clip_pos = camera.view_proj * world_pos;
out.colour = in.colour;
out.world_pos = world_pos.xyz;
let model3 = mat3x3<f32>(
object.model[0].xyz,
object.model[1].xyz,
object.model[2].xyz,
);
out.world_normal = normalize(model3 * in.normal);
out.world_tangent = vec4<f32>(normalize(model3 * in.tangent.xyz), in.tangent.w);
out.uv = in.uv;
// Read scalar attribute value for this vertex, guarded by has_attribute and buffer length.
let buf_len = arrayLength(&scalar_buffer);
let idx = in.vertex_index;
let has_attr = object.has_attribute != 0u && buf_len > 0u;
let safe_idx = min(idx, select(0u, buf_len - 1u, buf_len > 0u));
let raw_scalar = scalar_buffer[safe_idx];
out.scalar_val = select(0.0, raw_scalar, has_attr);
// Detect NaN before interpolation can corrupt the bit pattern.
let sv_bits = bitcast<u32>(raw_scalar);
let sv_is_nan = has_attr && (sv_bits & 0x7F800000u) == 0x7F800000u && (sv_bits & 0x007FFFFFu) != 0u;
out.is_nan_scalar = select(0.0, 1.0, sv_is_nan);
// Per-face RGBA colour (FaceColour attribute kind). Indexed by vertex_index which
// equals the sequential draw invocation counter for non-indexed face draws.
let fc_len = arrayLength(&face_colour_buffer);
let fc_idx = min(idx, select(0u, fc_len - 1u, fc_len > 0u));
out.face_colour = select(
vec4<f32>(1.0),
face_colour_buffer[fc_idx],
object.use_face_colour != 0u && fc_len > 0u,
);
return out;
}
// ---------------------------------------------------------------------------
// 32-sample Poisson disk (first 16 used for blocker search, all 32 for filter)
// ---------------------------------------------------------------------------
const POISSON_DISK: array<vec2<f32>, 32> = array<vec2<f32>, 32>(
vec2<f32>(-0.94201624, -0.39906216), vec2<f32>( 0.94558609, -0.76890725),
vec2<f32>(-0.09418410, -0.92938870), vec2<f32>( 0.34495938, 0.29387760),
vec2<f32>(-0.91588581, 0.45771432), vec2<f32>(-0.81544232, -0.87912464),
vec2<f32>(-0.38277543, 0.27676845), vec2<f32>( 0.97484398, 0.75648379),
vec2<f32>( 0.44323325, -0.97511554), vec2<f32>( 0.53742981, -0.47373420),
vec2<f32>(-0.26496911, -0.41893023), vec2<f32>( 0.79197514, 0.19090188),
vec2<f32>(-0.24188840, 0.99706507), vec2<f32>(-0.81409955, 0.91437590),
vec2<f32>( 0.19984126, 0.78641367), vec2<f32>( 0.14383161, -0.14100790),
vec2<f32>(-0.44451570, 0.67055830), vec2<f32>( 0.70509040, -0.15854630),
vec2<f32>( 0.07130650, -0.64599580), vec2<f32>( 0.39881030, 0.55789810),
vec2<f32>(-0.60554040, -0.34964830), vec2<f32>( 0.85095100, 0.47178830),
vec2<f32>(-0.47994860, 0.08443340), vec2<f32>(-0.12494190, -0.76098760),
vec2<f32>( 0.64839320, 0.74738240), vec2<f32>(-0.96815740, -0.12345680),
vec2<f32>( 0.27682050, -0.80927180), vec2<f32>(-0.73016460, 0.18344200),
vec2<f32>( 0.54754660, 0.06234570), vec2<f32>(-0.30967360, -0.61021430),
vec2<f32>(-0.57774330, 0.80459740), vec2<f32>( 0.18238670, -0.37596540),
);
// ---------------------------------------------------------------------------
// CSM shadow sampling : selects cascade by eye distance, samples atlas tile
// ---------------------------------------------------------------------------
fn sample_shadow_csm(
world_pos: vec3<f32>,
eye_pos: vec3<f32>,
surface_normal: vec3<f32>,
light_dir: vec3<f32>,
) -> f32 {
let dist = dot(world_pos - eye_pos, camera.forward);
// Select cascade based on camera-forward depth, which matches the
// frustum depth intervals used to build the cascade matrices.
var cascade_idx = 0u;
for (var i = 0u; i < shadow_atlas.cascade_count; i++) {
if dist > shadow_atlas.cascade_splits[i] {
cascade_idx = i + 1u;
}
}
cascade_idx = min(cascade_idx, shadow_atlas.cascade_count - 1u);
// Project the actual surface position to get the correct shadow-map UV.
// We must NOT offset the UV : on curved surfaces the tangential component
// of the normal would shift the sample into a shallower shadow-map region
// (closer to the light), causing MORE false shadows instead of fewer.
let light_clip = shadow_atlas.cascade_vp[cascade_idx] * vec4<f32>(world_pos, 1.0);
let ndc = light_clip.xyz / light_clip.w;
// NDC -> tile UV [0,1].
let tile_uv = vec2<f32>(ndc.x * 0.5 + 0.5, -ndc.y * 0.5 + 0.5);
// Out-of-range check.
if tile_uv.x < 0.0 || tile_uv.x > 1.0 || tile_uv.y < 0.0 || tile_uv.y > 1.0 ||
ndc.z < 0.0 || ndc.z > 1.0 {
return 1.0;
}
// Remap tile UV through atlas rect.
let rect = shadow_atlas.atlas_rects[cascade_idx];
let atlas_uv = vec2<f32>(
mix(rect.x, rect.z, tile_uv.x),
mix(rect.y, rect.w, tile_uv.y),
);
let texel_size = 1.0 / shadow_atlas.atlas_size;
// Normal-offset depth bias: move the comparison point toward the light so
// the receiver sample does not self-intersect the shadow caster. Increase
// the offset near grazing angles, where curved surfaces are most prone to
// shadow-terminator acne.
//
// Scale the bias by the cascade's world-space texel size so that far
// cascades (which cover much larger world areas per texel) get proportionally
// more bias. cascade_vp[i][0][0] = 2 / world_extent_x for the ortho proj,
// so world_per_texel = 2 / (scale * atlas_size * tile_fraction).
let n_dot_l = dot(surface_normal, light_dir);
let offset_sign = select(-1.0, 1.0, n_dot_l >= 0.0);
let texel_world = 2.0 / (shadow_atlas.cascade_vp[cascade_idx][0][0] * shadow_atlas.atlas_size * (rect.z - rect.x));
let normal_bias = texel_world * mix(1.5, 0.5, clamp(abs(n_dot_l), 0.0, 1.0));
let offset_world = world_pos + surface_normal * (offset_sign * normal_bias);
let offset_clip = shadow_atlas.cascade_vp[cascade_idx] * vec4<f32>(offset_world, 1.0);
let biased_depth = (offset_clip.xyz / offset_clip.w).z - lights_uniform.shadow_bias;
// Per-fragment Poisson disk rotation : breaks up the coherent square/blob
// pattern that results from every pixel using the same disk orientation.
// Uses world_pos.xz as seed so adjacent pixels get different rotations.
let noise = fract(52.9829189 * fract(dot(world_pos.xz, vec2<f32>(0.06711056, 0.00583715))));
let rot = noise * 6.28318530;
let sin_r = sin(rot);
let cos_r = cos(rot);
if shadow_atlas.shadow_filter == 1u {
// ---------------------------------------------------------------
// PCSS: blocker search -> penumbra estimation -> variable PCF
// ---------------------------------------------------------------
let search_radius = shadow_atlas.pcss_light_radius * 16.0 * texel_size;
// Phase 1: Blocker search (16 Poisson samples).
var blocker_sum = 0.0;
var blocker_count = 0.0;
for (var i = 0u; i < 16u; i++) {
let d = POISSON_DISK[i];
let rd = vec2<f32>(d.x * cos_r - d.y * sin_r, d.x * sin_r + d.y * cos_r);
let sample_uv = atlas_uv + rd * search_radius;
let clamped_uv = clamp(sample_uv, rect.xy, rect.zw);
let sample_depth = textureSampleCompare(shadow_map, shadow_sampler, clamped_uv, biased_depth);
if sample_depth < 1.0 {
let coords = vec2<i32>(clamped_uv * shadow_atlas.atlas_size);
let raw_depth = textureLoad(shadow_map, coords, 0);
blocker_sum += raw_depth;
blocker_count += 1.0;
}
}
if blocker_count < 1.0 {
return 1.0;
}
let avg_blocker = blocker_sum / blocker_count;
let penumbra_width = shadow_atlas.pcss_light_radius * (biased_depth - avg_blocker) / max(avg_blocker, 0.001);
let filter_radius = max(penumbra_width * 16.0 * texel_size, texel_size);
// Phase 2: Variable-width PCF (32 Poisson samples).
var shadow = 0.0;
for (var i = 0u; i < 32u; i++) {
let d = POISSON_DISK[i];
let rd = vec2<f32>(d.x * cos_r - d.y * sin_r, d.x * sin_r + d.y * cos_r);
let sample_uv = atlas_uv + rd * filter_radius;
let clamped_uv = clamp(sample_uv, rect.xy, rect.zw);
shadow += textureSampleCompare(shadow_map, shadow_sampler, clamped_uv, biased_depth);
}
return shadow / 32.0;
} else {
// ---------------------------------------------------------------
// 32-sample Poisson-disk PCF at 4-texel radius, per-fragment rotation.
// ---------------------------------------------------------------
let pcf_radius = 4.0 * texel_size;
var shadow = 0.0;
for (var i = 0u; i < 32u; i++) {
let d = POISSON_DISK[i];
let rd = vec2<f32>(d.x * cos_r - d.y * sin_r, d.x * sin_r + d.y * cos_r);
let sample_uv = atlas_uv + rd * pcf_radius;
let clamped_uv = clamp(sample_uv, rect.xy, rect.zw);
shadow += textureSampleCompare(shadow_map, shadow_sampler, clamped_uv, biased_depth);
}
return shadow / 32.0;
}
}
// ---------------------------------------------------------------------------
// PBR BRDF helpers (Cook-Torrance)
// ---------------------------------------------------------------------------
fn D_GGX(NdotH: f32, roughness: f32) -> f32 {
let a = roughness * roughness;
let a2 = a * a;
let denom = NdotH * NdotH * (a2 - 1.0) + 1.0;
return a2 / (3.14159265 * denom * denom);
}
fn G1_Smith(NdotV: f32, roughness: f32) -> f32 {
let r = roughness + 1.0;
let k = (r * r) / 8.0;
return NdotV / (NdotV * (1.0 - k) + k);
}
fn G_Smith(NdotV: f32, NdotL: f32, roughness: f32) -> f32 {
return G1_Smith(NdotV, roughness) * G1_Smith(NdotL, roughness);
}
fn F_Schlick(cos_theta: f32, F0: vec3<f32>) -> vec3<f32> {
return F0 + (vec3<f32>(1.0) - F0) * pow(clamp(1.0 - cos_theta, 0.0, 1.0), 5.0);
}
// ---------------------------------------------------------------------------
// IBL helpers : equirectangular sampling
// This is the CANONICAL copy. Keep in sync with:
// mesh_instanced.wgsl, mesh_oit.wgsl, mesh_instanced_oit.wgsl
// ---------------------------------------------------------------------------
const IBL_PI: f32 = 3.14159265;
/// Convert a world-space direction to equirectangular UV, applying optional Y-rotation.
fn dir_to_equirect_uv(dir: vec3<f32>, rotation: f32) -> vec2<f32> {
let s = sin(rotation);
let c = cos(rotation);
let d = vec3<f32>(c * dir.x + s * dir.z, dir.y, -s * dir.x + c * dir.z);
let phi = atan2(d.z, d.x); // -PI..PI
let theta = asin(clamp(d.y, -1.0, 1.0)); // -PI/2..PI/2
return vec2<f32>(0.5 + phi / (2.0 * IBL_PI), 0.5 - theta / IBL_PI);
}
/// Sample the irradiance map (diffuse IBL).
fn sample_ibl_irradiance(N: vec3<f32>, rotation: f32) -> vec3<f32> {
let uv = dir_to_equirect_uv(N, rotation);
return textureSampleLevel(ibl_irradiance, ibl_sampler, uv, 0.0).rgb;
}
/// Sample the prefiltered specular map at a roughness-derived mip level.
fn sample_ibl_prefiltered(R: vec3<f32>, roughness: f32, rotation: f32) -> vec3<f32> {
let uv = dir_to_equirect_uv(R, rotation);
let max_mip = 4.0; // 5 mip levels -> max index 4
let mip = roughness * max_mip;
return textureSampleLevel(ibl_prefiltered, ibl_sampler, uv, mip).rgb;
}
/// Look up the BRDF integration LUT (x=NdotV, y=roughness).
fn sample_brdf_lut(NdotV: f32, roughness: f32) -> vec2<f32> {
return textureSampleLevel(ibl_brdf_lut, ibl_sampler, vec2<f32>(NdotV, roughness), 0.0).rg;
}
/// Full IBL ambient: diffuse irradiance + specular split-sum.
fn ibl_ambient(
N: vec3<f32>,
V: vec3<f32>,
base_colour: vec3<f32>,
metallic: f32,
roughness: f32,
F0: vec3<f32>,
ao: f32,
intensity: f32,
rotation: f32,
) -> vec3<f32> {
let NdotV = max(dot(N, V), 0.001);
let F = F_Schlick_roughness(NdotV, F0, roughness);
let kS = F;
let kD = (vec3<f32>(1.0) - kS) * (1.0 - metallic);
// Diffuse IBL.
let irradiance = sample_ibl_irradiance(N, rotation);
let diffuse_ibl = kD * irradiance * base_colour;
// Specular IBL (split-sum approximation).
let R = reflect(-V, N);
let prefiltered = sample_ibl_prefiltered(R, roughness, rotation);
let brdf = sample_brdf_lut(NdotV, roughness);
let specular_ibl = prefiltered * (F * brdf.x + brdf.y);
return (diffuse_ibl + specular_ibl) * ao * intensity;
}
fn F_Schlick_roughness(cos_theta: f32, F0: vec3<f32>, roughness: f32) -> vec3<f32> {
return F0 + (max(vec3<f32>(1.0 - roughness), F0) - F0) * pow(clamp(1.0 - cos_theta, 0.0, 1.0), 5.0);
}
fn pbr_light_contrib(
N: vec3<f32>,
V: vec3<f32>,
L: vec3<f32>,
radiance: vec3<f32>,
base_colour: vec3<f32>,
metallic: f32,
roughness: f32,
F0: vec3<f32>,
) -> vec3<f32> {
let H = normalize(L + V);
let NdotL = max(dot(N, L), 0.0);
if NdotL <= 0.0 { return vec3<f32>(0.0); }
let NdotV = max(dot(N, V), 0.001);
let NdotH = max(dot(N, H), 0.0);
let HdotV = max(dot(H, V), 0.0);
let D = D_GGX(NdotH, roughness);
let G = G_Smith(NdotV, NdotL, roughness);
let F = F_Schlick(HdotV, F0);
let kS = F;
let kD = (vec3<f32>(1.0) - kS) * (1.0 - metallic);
let specular = (D * G * F) / (4.0 * NdotV * NdotL + 0.001);
return (kD * base_colour / 3.14159265 + specular) * radiance * NdotL;
}
// UV parameterization visualization : returns a procedural RGB colour from UV coordinates.
// mode: 1=checker, 2=grid, 3=localcheck (polar checker), 4=localrad (concentric rings).
// scale: tile frequency multiplier applied to uv before pattern evaluation.
fn param_vis_colour(uv: vec2<f32>, mode: u32, scale: f32) -> vec3<f32> {
let col_a = vec3<f32>(0.85, 0.85, 0.85);
let col_b = vec3<f32>(0.2, 0.2, 0.2);
let line_col = vec3<f32>(0.1, 0.1, 0.1);
let bg_col = vec3<f32>(0.85, 0.85, 0.85);
let line_width = 0.05f;
let su = uv.x * scale;
let sv = uv.y * scale;
if mode == 1u {
// Checker: alternating squares in UV space.
let p = (i32(floor(su)) + i32(floor(sv))) & 1;
return select(col_a, col_b, p != 0);
} else if mode == 2u {
// Grid: thin lines at UV integer boundaries.
let on_line = fract(su) < line_width || fract(sv) < line_width;
return select(bg_col, line_col, on_line);
} else if mode == 3u {
// LocalChecker: polar checkerboard centred at UV (0.5, 0.5).
let d = uv - vec2<f32>(0.5);
let r = length(d) * scale * 2.0;
let theta = atan2(d.y, d.x);
let ring = i32(floor(r)) & 1;
let sector = i32(floor(theta * 4.0 / 3.14159265 + 8.0)) & 1;
return select(col_a, col_b, (ring ^ sector) != 0);
} else {
// LocalRadial: concentric rings centred at UV (0.5, 0.5).
let r = length(uv - vec2<f32>(0.5)) * scale * 2.0;
return select(col_a, col_b, (i32(floor(r)) & 1) != 0);
}
}
@fragment
fn fs_main(in: VertexOut, @builtin(front_facing) is_front: bool) -> @location(0) vec4<f32> {
// Section view: discard fragment if it falls on the clipped side of any plane.
for (var i = 0u; i < clip_planes.count; i++) {
let plane = clip_planes.planes[i];
if dot(in.world_pos, plane.xyz) + plane.w < 0.0 {
discard;
}
}
if !clip_volume_test(in.world_pos) { discard; }
// Wireframe mode: override colour to gray, no lighting.
if object.wireframe != 0u {
return vec4<f32>(0.75, 0.75, 0.75, 1.0);
}
// Sample texture if one is assigned; fallback texture is 1x1 white (neutral multiply).
var tex_colour = vec4<f32>(1.0);
if object.has_texture == 1u {
tex_colour = textureSample(obj_texture, obj_sampler, in.uv);
}
let obj_colour = vec4<f32>(object.colour.rgb * in.colour.rgb * tex_colour.rgb,
object.colour.a * in.colour.a * tex_colour.a);
var base_colour = obj_colour.rgb;
// Scalar attribute colour override: sample LUT when has_attribute is set.
if object.has_attribute != 0u {
if in.is_nan_scalar > 0.5 {
if object.use_nan_colour == 0u {
discard;
}
return vec4<f32>(object.nan_colour.rgb, object.nan_colour.a);
}
let raw = in.scalar_val;
let range = object.scalar_max - object.scalar_min;
let t = clamp(
select(0.0, (raw - object.scalar_min) / range, range > 0.0001),
0.0, 1.0,
);
base_colour = textureSampleLevel(lut_texture, lut_sampler, vec2<f32>(t, 0.5), 0.0).rgb;
}
// Per-face RGBA colour: use directly, bypassing all lighting and colourmap logic.
if object.use_face_colour != 0u {
var fc = in.face_colour;
if object.selected != 0u {
fc = mix(fc, vec4<f32>(1.0, 0.55, 0.1, 1.0), 0.35);
}
return vec4<f32>(fc.rgb, fc.a * object.colour.a);
}
// Unlit: skip all lighting, return raw colour directly.
if object.unlit != 0u {
return vec4<f32>(base_colour, obj_colour.a);
}
// Resolve shading normal: TBN normal mapping or geometric normal.
var N: vec3<f32>;
if object.has_normal_map != 0u {
let nm_sample = textureSample(normal_map, obj_sampler, in.uv).rgb;
let ts_normal = normalize(nm_sample * 2.0 - vec3<f32>(1.0));
let T = normalize(in.world_tangent.xyz);
let Ng = normalize(in.world_normal);
let T_orth = normalize(T - dot(T, Ng) * Ng);
let B = cross(Ng, T_orth) * in.world_tangent.w;
let TBN = mat3x3<f32>(T_orth, B, Ng);
N = normalize(TBN * ts_normal);
} else {
N = normalize(in.world_normal);
}
// Back-face policy handling: flip normal and optionally override colour for back faces.
// Runs before matcap/uv_vis/PBR so all downstream lighting paths use the substituted values.
// 0=Cull, 1=Identical, 2=DifferentColour, 3=Tint, 4=Checker, 5=Hatching, 6=Crosshatch, 7=Stripes.
if !is_front && object.backface_policy >= 2u {
N = -N;
if object.backface_policy == 2u {
// DifferentColour: replace base_colour entirely.
base_colour = object.backface_colour.rgb;
} else if object.backface_policy == 3u {
// Tint: darken base_colour by factor stored in backface_colour.r.
base_colour = base_colour * (1.0 - object.backface_colour.r);
} else {
// Pattern modes (4..7): procedural pattern scaled to object size.
let pattern_colour = object.backface_colour.rgb;
let pattern_type = object.backface_policy - 4u;
let wp = in.world_pos * object.backface_colour.w;
var use_pattern = false;
if pattern_type == 0u {
// Checker: alternating squares in world XZ.
let p = (i32(floor(wp.x)) + i32(floor(wp.z))) & 1;
use_pattern = p != 0;
} else if pattern_type == 1u {
// Hatching: diagonal lines at 45 degrees.
use_pattern = fract((wp.x + wp.z) * 0.5) < 0.4;
} else if pattern_type == 2u {
// Crosshatch: two sets of diagonal lines.
use_pattern = fract((wp.x + wp.z) * 0.5) < 0.3 || fract((wp.x - wp.z) * 0.5) < 0.3;
} else {
// Stripes: horizontal lines in world Z.
use_pattern = fract(wp.z * 0.5) < 0.4;
}
base_colour = select(base_colour, pattern_colour, use_pattern);
}
}
// AO factor from AO map.
var ao_factor = 1.0;
if object.has_ao_map != 0u {
ao_factor = textureSample(ao_map, obj_sampler, in.uv).r;
}
// Matcap shading : the matcap texture encodes material appearance as a sphere-space lookup.
// UV is derived from the view-space normal (x,y components).
if object.use_matcap != 0u {
// Transform world-space shading normal to view space (rotation only, w=0).
let view_normal = normalize((camera.view * vec4<f32>(N, 0.0)).xyz);
// Map view-space normal XY to UV.
// Convention: -ny*0.5+0.5 so that normals pointing UP map to v=0 (top of
// texture) which is where built-in matcaps place the bright region.
//
// Clamp the XY radius to 0.99 to stay just inside the matcap disc.
// At grazing angles (silhouette) |view_normal.xy| -> 1, which samples the
// transparent black border of the matcap image, producing a dark dotted band.
let mc_len = length(view_normal.xy);
let mc_scale = select(1.0, 0.99 / mc_len, mc_len > 0.99);
let matcap_uv = vec2<f32>(
view_normal.x * mc_scale * 0.5 + 0.5,
-view_normal.y * mc_scale * 0.5 + 0.5,
);
let mc = textureSample(matcap_texture, obj_sampler, matcap_uv);
if object.matcap_blendable != 0u {
// Blendable: RGB is the matcap colour; A tints the base geometry colour.
let blended = clamp(mc.rgb + mc.a * base_colour, vec3<f32>(0.0), vec3<f32>(1.0));
return vec4<f32>(blended, obj_colour.a);
} else {
// Static: matcap RGB fully overrides the object colour.
return vec4<f32>(mc.rgb, obj_colour.a);
}
}
// UV parameterization visualization: procedural pattern replaces all lighting.
if object.uv_vis_mode != 0u {
let vis = param_vis_colour(in.uv, object.uv_vis_mode, object.uv_vis_scale);
return vec4<f32>(vis, obj_colour.a);
}
// Use the smooth vertex normal for shadow bias. Screen-space derivatives
// (dpdx/dpdy) become unreliable when the surface covers few pixels (zoomed
// out) because edge fragments include helper invocations with undefined
// world_pos, producing garbage normals that flip offset_sign and cause
// self-shadowing. N is correctly interpolated and stable at all distances.
let shadow_normal = N;
let V = normalize(camera.eye_pos - in.world_pos);
let tint = vec4<f32>(1.0, 1.0, 1.0, 1.0);
var final_rgb: vec3<f32>;
if object.use_pbr != 0u {
// Cook-Torrance PBR path
let metallic = clamp(object.metallic, 0.0, 1.0);
let roughness = max(object.roughness, 0.04);
let F0 = mix(vec3<f32>(0.04), base_colour, metallic);
var Lo = vec3<f32>(0.0);
for (var i = 0u; i < lights_uniform.count; i++) {
let l = lights_uniform.lights[i];
var L: vec3<f32>;
var radiance: vec3<f32>;
if l.light_type == 0u {
L = normalize(l.pos_or_dir);
radiance = l.colour * l.intensity;
} else if l.light_type == 1u {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
L = to_light / max(dist, 0.0001);
let falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
radiance = l.colour * l.intensity * falloff * falloff;
} else {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
L = to_light / max(dist, 0.0001);
let dist_falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
let spot_dir = normalize(l.spot_direction);
let cos_angle = dot(-L, spot_dir);
let cos_outer = cos(l.outer_angle);
let cos_inner = cos(l.inner_angle);
let cone_att = clamp(
(cos_angle - cos_outer) / max(cos_inner - cos_outer, 0.0001),
0.0, 1.0,
);
radiance = l.colour * l.intensity * dist_falloff * dist_falloff * cone_att;
}
// Shadow factor (lights[0] only) : CSM.
var shadow_factor = 1.0;
if i == 0u && lights_uniform.shadows_enabled != 0u {
shadow_factor = sample_shadow_csm(in.world_pos, camera.eye_pos, shadow_normal, L);
// Fade shadow to 1.0 near the terminator (N·L ≈ 0).
// Shadow-map texels project at grazing angles near the terminator,
// causing visible squares. N·L already smoothly darkens that region,
// so we suppress the shadow map there.
let terminator = smoothstep(0.0, 0.75, dot(shadow_normal, L));
shadow_factor = mix(1.0, shadow_factor, terminator);
}
radiance *= shadow_factor;
Lo += pbr_light_contrib(N, V, L, radiance, base_colour,
metallic, roughness, F0);
}
// Ambient: IBL when enabled, hemisphere fallback otherwise.
var ambient: vec3<f32>;
if lights_uniform.ibl_enabled != 0u {
ambient = ibl_ambient(N, V, base_colour, metallic, roughness, F0,
ao_factor, lights_uniform.ibl_intensity,
lights_uniform.ibl_rotation);
} else {
let hemi_t = clamp(in.world_normal.y * 0.5 + 0.5, 0.0, 1.0);
let hemi_colour = mix(lights_uniform.ground_colour, lights_uniform.sky_colour, hemi_t);
let ambient_scale = vec3<f32>(object.ambient) + hemi_colour * lights_uniform.hemisphere_intensity;
ambient = ambient_scale * (base_colour * (1.0 - metallic) + F0 * metallic) * ao_factor;
}
final_rgb = clamp((Lo + ambient) * tint.rgb, vec3<f32>(0.0), vec3<f32>(1.0));
} else {
// Multi-light Blinn-Phong path
var total_colour_contrib = vec3<f32>(0.0);
for (var i = 0u; i < lights_uniform.count; i++) {
let l = lights_uniform.lights[i];
var light_dir: vec3<f32>;
var attenuation = 1.0;
if l.light_type == 0u {
light_dir = normalize(l.pos_or_dir);
} else if l.light_type == 1u {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
light_dir = to_light / max(dist, 0.0001);
let falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
attenuation = falloff * falloff;
} else {
let to_light = l.pos_or_dir - in.world_pos;
let dist = length(to_light);
light_dir = to_light / max(dist, 0.0001);
let dist_falloff = clamp(1.0 - dist / l.range, 0.0, 1.0);
let spot_dir = normalize(l.spot_direction);
let cos_angle = dot(-light_dir, spot_dir);
let cos_outer = cos(l.outer_angle);
let cos_inner = cos(l.inner_angle);
let cone_att = clamp(
(cos_angle - cos_outer) / max(cos_inner - cos_outer, 0.0001),
0.0, 1.0,
);
attenuation = dist_falloff * dist_falloff * cone_att;
}
var shadow = 1.0;
if i == 0u && lights_uniform.shadows_enabled != 0u {
shadow = sample_shadow_csm(in.world_pos, camera.eye_pos, shadow_normal, light_dir);
// Terminator fade: suppress shadow map near N·L ≈ 0 to avoid
// shadow-texel squares on curved surfaces.
let terminator = smoothstep(0.0, 0.75, dot(shadow_normal, light_dir));
shadow = mix(1.0, shadow, terminator);
}
let H = normalize(light_dir + V);
let n_dot_l = max(dot(N, light_dir), 0.0);
let n_dot_h = max(dot(N, H), 0.0);
let diffuse_contrib = object.diffuse * n_dot_l * l.intensity * attenuation * shadow;
let specular_contrib = object.specular * pow(n_dot_h, object.shininess)
* l.intensity * attenuation * shadow;
total_colour_contrib += (diffuse_contrib + specular_contrib) * l.colour;
}
let ambient_contrib = object.ambient;
let hemi_t = clamp(in.world_normal.y * 0.5 + 0.5, 0.0, 1.0);
let hemi_colour = mix(lights_uniform.ground_colour, lights_uniform.sky_colour, hemi_t);
let hemi_ambient = hemi_colour * lights_uniform.hemisphere_intensity;
let lit_rgb = base_colour * (ambient_contrib + hemi_ambient) * ao_factor
+ base_colour * total_colour_contrib;
final_rgb = clamp(lit_rgb * tint.rgb, vec3<f32>(0.0), vec3<f32>(1.0));
}
return vec4<f32>(final_rgb, obj_colour.a);
}